TB-500 Dosage: The Complete Protocol Guide (Research Data + Cycling)
Written by Alejandro Reyes
Founder & Lead Researcher
Reviewed by Peptide Nerds Editorial · Updated April 2026
TB-500 Dosage: The Complete Protocol Guide (Research Data + Cycling)
Important: This article is for educational purposes only. We are not doctors. Nothing here is medical advice. Talk to a qualified healthcare provider before starting any peptide protocol.
The Bottom Line
- TB-500 is a recovery and healing peptide. It is a lab-made version of a protein your body already produces called thymosin beta-4, which helps repair damaged tissue.
- The typical dose is 2-5 mg injected under the skin twice per week during a loading phase, then 2 mg once per week for maintenance.
- A full cycle runs 8-12 weeks on, then 4 weeks off. The loading phase covers the first 4-6 weeks.
- TB-500 is often stacked with BPC-157. This combo is called the "Wolverine stack" because they target healing through different pathways. No human study has tested the combination.
- Most of the tissue repair evidence comes from animal studies and lab experiments. Human safety data exists from two Phase 1 trials, but no one has tested these doses in humans for injury recovery.
- TB-500 is banned by WADA. If you compete in any tested sport, this is a prohibited substance.
Key Takeaways
- TB-500 is a synthetic version of a 43-amino acid region of thymosin beta-4, a naturally occurring peptide involved in tissue repair, cell migration, and inflammation control. It is not FDA-approved for human use.
- The most commonly reported research protocol uses a loading phase of 2-5mg injected subcutaneously twice per week for 4-6 weeks, followed by a maintenance phase of 2mg once per week.
- Thymosin beta-4 has been studied in Phase 1 human safety trials. Intravenous doses up to 1,260mg in healthy volunteers showed no dose-limiting toxicities and no serious adverse events (PMID: 20536472).
- A separate Phase 1 trial of recombinant human thymosin beta-4 at doses of 0.05-25 mcg/kg IV confirmed safety with only mild to moderate adverse events (PMID: 34346165).
- TB-500 is typically cycled 8-12 weeks on, 4 weeks off. There is no published human data establishing an optimal cycle length.
- TB-500 is a WADA prohibited substance. It is banned in all competitive sports under the World Anti-Doping Agency's peptide hormone category.
- Human clinical data is extremely limited. Most tissue repair and wound healing evidence comes from animal models and in vitro studies. This gap matters and should inform your risk assessment.
Note: TB-500 is classified as a research compound. It is not FDA-approved for any human indication. The dosing information below comes from research literature, animal studies, and limited Phase 1 human safety data. This is not a recommendation to use this compound. Consult a qualified healthcare provider.
What Is TB-500?
TB-500 is a synthetic peptide. It replicates the active region of thymosin beta-4 (often written as Tbeta4 or TB4), a 43-amino acid peptide that your body produces naturally.
Thymosin beta-4 was first isolated from bovine thymus tissue over 40 years ago. It is present in nearly all human tissues and found at high concentrations in blood platelets, wound fluid, and white blood cells (PMID: 17947592).
Its primary intracellular function is regulating actin, a protein that forms the structural framework of cells. By sequestering actin, thymosin beta-4 controls cell migration, which is a key step in wound healing. When tissue gets damaged, platelets and macrophages release thymosin beta-4 at the injury site.
The research interest in TB-500 centers on several documented biological activities:
Cell migration. Thymosin beta-4 promotes the movement of endothelial cells, keratinocytes, and stem/progenitor cells toward injured tissue. This is the foundation of its wound healing effects (PMID: 22074294).
Angiogenesis. It stimulates formation of new blood vessels. Animal studies show thymosin beta-4 plays a role in vasculogenesis, angiogenesis, and arteriogenesis in developing cardiac tissue (PMID: 17947592).
Anti-inflammatory activity. Thymosin beta-4 downregulates inflammatory chemokines and cytokines. In corneal wound models, it reduced PMN infiltration and decreased mRNA levels of IL-1beta, MIP-1alpha, MIP-2, and MCP-1 (PMID: 11950239).
Anti-fibrotic effects. It reduces the conversion of fibroblasts to myofibroblasts, resulting in less scar tissue formation. Its N-terminal fragment Ac-SDKP has shown efficacy in animal models of liver, lung, heart, and kidney fibrosis (PMID: 36580759).
Cell survival. Thymosin beta-4 reduces apoptosis (programmed cell death) in damaged tissue, potentially preserving more viable cells during the recovery window (PMID: 22074294).
The distinction between thymosin beta-4 and TB-500 matters. Thymosin beta-4 is the full-length, naturally occurring 43-amino acid peptide. TB-500 is a synthetic fragment designed to replicate its active region. Research literature almost exclusively studies thymosin beta-4 itself, not the TB-500 fragment. Findings from thymosin beta-4 studies are applied to TB-500, but they are not identical molecules.
TB-500 Dosage: What Research Protocols Report
TB-500 is not FDA-approved. There is no official prescribing label or standardized dosing guideline. The protocols below come from research literature, animal study dosing extrapolations, and clinical practice observations.
Loading Phase
The most commonly reported loading protocol:
- Dose: 2-5mg per injection
- Frequency: Twice per week (separated by 3-4 days)
- Duration: 4-6 weeks
- Route: Subcutaneous injection
The purpose of the loading phase is to build circulating levels of the peptide and saturate target tissues. Most protocols start at 2-2.5mg twice weekly. Some increase to 5mg twice weekly for acute injury situations, though no human dose-response data supports one loading dose over another.
Total weekly loading dose: 4-10mg per week, depending on the protocol.
Maintenance Phase
After the loading phase:
- Dose: 2mg per injection
- Frequency: Once per week or once every two weeks
- Duration: Varies by protocol (typically continues through the remainder of the cycle)
The maintenance phase drops both dose and frequency. The logic is that tissue repair processes initiated during loading continue with less exogenous support.
Dosage Summary Table
| Phase | Dose Per Injection | Frequency | Duration |
|---|---|---|---|
| Loading (standard) | 2-2.5mg | Twice weekly | 4-6 weeks |
| Loading (aggressive) | 4-5mg | Twice weekly | 4-6 weeks |
| Maintenance | 2mg | Once weekly | 4-6 weeks |
| Maintenance (extended) | 2mg | Every 2 weeks | Varies |
Important Context on These Numbers
These dosing protocols are not derived from controlled human clinical trials for tissue repair. The Phase 1 safety trials of thymosin beta-4 used intravenous administration at much higher absolute doses (42-1,260mg) to establish safety profiles, not therapeutic dosing for musculoskeletal repair (PMID: 20536472).
The subcutaneous dosing protocols circulating in research communities are largely extrapolated from animal study data and practitioner observation. Treat them accordingly.
How to Reconstitute TB-500
TB-500 typically comes as a lyophilized (freeze-dried) powder in 5mg or 10mg vials. Reconstitution is required before injection.
What you need: TB-500 lyophilized powder vial, bacteriostatic water for injection, insulin syringe (typically 1mL/100 unit), alcohol prep pads, clean surface.
Step 1. Scrub the rubber stopper of both the peptide vial and bacteriostatic water vial with an alcohol prep pad. Let air dry for 5-10 seconds.
Step 2. Draw the appropriate volume of bacteriostatic water into the syringe. See the reconstitution math below for your specific vial size.
Step 3. Insert the needle into the TB-500 vial at an angle. Let the water run down the inside glass wall. Do not spray it directly onto the powder. Direct force can break peptide bonds and reduce potency.
Step 4. Gently swirl the vial in a slow circular motion until the powder fully dissolves. Do not shake. Shaking creates foam and can damage the peptide.
Step 5. Inspect the solution. It should be clear and colorless. Do not use if cloudy, discolored, or if you see particles.
Step 6. Refrigerate the reconstituted vial at 2-8 degrees Celsius. Use within 3-4 weeks. Do not freeze after reconstitution.
Reconstitution Math: 5mg Vial
| Bacteriostatic Water Added | Concentration | Volume for 2mg Dose | Volume for 2.5mg Dose |
|---|---|---|---|
| 1mL | 5mg/mL | 0.40mL (40 units) | 0.50mL (50 units) |
| 2mL | 2.5mg/mL | 0.80mL (80 units) | 1.00mL (100 units) |
Reconstitution Math: 10mg Vial
| Bacteriostatic Water Added | Concentration | Volume for 2mg Dose | Volume for 2.5mg Dose |
|---|---|---|---|
| 2mL | 5mg/mL | 0.40mL (40 units) | 0.50mL (50 units) |
| 3mL | 3.33mg/mL | 0.60mL (60 units) | 0.75mL (75 units) |
| 4mL | 2.5mg/mL | 0.80mL (80 units) | 1.00mL (100 units) |
Practical tip: Adding 2mL of bacteriostatic water to a 5mg vial (2.5mg/mL concentration) makes dosing straightforward. A 2mg dose equals 0.80mL (80 units on an insulin syringe). A 2.5mg dose equals 1.00mL (a full syringe).
For a complete walkthrough of reconstitution technique applicable to all peptides, see our how to reconstitute peptides guide.
Injection Protocol
Route: Subcutaneous (under the skin). TB-500 is not typically administered intramuscularly or intravenously in research settings outside of clinical trials.
Common sites: Lower abdomen (2+ inches from the navel), upper thigh, upper arm.
Technique: Pinch a fold of skin at the injection site, insert needle at 45-90 degrees depending on body fat, inject slowly, withdraw.
Rotation: Rotate injection sites with each dose to reduce irritation and prevent scar tissue buildup.
Some research protocols inject TB-500 near the site of injury. Published evidence does not confirm whether local injection produces better results than distant subcutaneous injection for this peptide. Thymosin beta-4 is a small peptide with systemic distribution, so the rationale for localized injection is theoretical.
TB-500 Cycle Length and Cycling Protocol
Standard Cycling Structure
| Protocol | On Duration | Off Duration | Total Cycle |
|---|---|---|---|
| Standard | 8-12 weeks | 4 weeks | 12-16 weeks |
| Short (acute injury) | 6-8 weeks | 4 weeks | 10-12 weeks |
| Extended | 12-16 weeks | 4-6 weeks | 16-22 weeks |
A typical 12-week cycle would look like:
- Weeks 1-4: Loading phase, 2.5mg twice weekly (5mg/week)
- Weeks 5-8: Maintenance phase, 2mg once weekly
- Weeks 9-12: Continue maintenance or taper to 2mg every two weeks
- Weeks 13-16: Off (no TB-500)
Why Cycle?
No published research definitively establishes whether cycling TB-500 is necessary. The rationale is theoretical: periodic breaks may prevent receptor desensitization and allow the body's endogenous repair mechanisms to function without exogenous support. Cost is also a factor, since research peptides are not cheap.
TB-500 vs. BPC-157: Dosage and Mechanism Comparison
TB-500 and BPC-157 are the two most commonly discussed research peptides for tissue repair. They work through different mechanisms, and some research protocols combine them.
| Feature | TB-500 | BPC-157 |
|---|---|---|
| Origin | Synthetic fragment of thymosin beta-4 (thymus-derived) | Synthetic peptide derived from gastric juice protein |
| Size | 43 amino acids (full thymosin beta-4) | 15 amino acids |
| Primary mechanism | Actin regulation, cell migration, angiogenesis | Nitric oxide system modulation, growth factor upregulation |
| Typical research dose | 2-5mg, 1-2x weekly | 250-500mcg, 1-2x daily |
| Route | Subcutaneous | Subcutaneous or oral |
| Loading phase | Yes (4-6 weeks) | Not standard |
| FDA approved | No | No |
| Human clinical trials | Phase 1 safety data exists | Limited |
The "Wolverine Stack": Some research protocols combine TB-500 and BPC-157, based on the theory that their complementary mechanisms produce additive tissue repair effects. TB-500 addresses the structural migration and blood vessel formation side. BPC-157 addresses growth factor signaling and nitric oxide pathways. No published clinical trial has tested this combination in humans. The name is community-derived, not scientific. For BPC-157 dosing specifics, see our BPC-157 dosage guide.
What the Human Safety Data Actually Shows
This section matters. The gap between animal data and human data for TB-500 is significant. Here is what exists.
Phase 1 Trial: Ruff et al. (2010)
A randomized, placebo-controlled, single and multiple dose study tested synthetic thymosin beta-4 intravenously in 40 healthy volunteers across four cohorts. Doses ranged from 42mg to 1,260mg IV. After single-dose safety review, subjects received the same dose daily for 14 days (PMID: 20536472).
Key findings:
- Adverse events were infrequent, mild, or moderate
- No dose-limiting toxicities at any dose level
- No serious adverse events
- Pharmacokinetics showed dose-proportional response
- Half-life increased with increasing dose
Phase 1 Trial: Wang et al. (2021)
A first-in-human trial of recombinant human thymosin beta-4 in 84 healthy Chinese volunteers tested single IV doses from 0.05 to 25 mcg/kg and multiple daily doses (0.5, 2.0, 5.0 mcg/kg for 10 days) (PMID: 34346165).
Key findings:
- Adverse events were mild to moderate
- No dose-limiting toxicities or serious adverse events
- No obvious accumulation after continuous administration
- Plasma concentration and AUC increased proportionally with dose
Phase 2 Clinical Data (Topical/Ophthalmic)
A Phase 2 randomized trial tested thymosin beta-4 eye drops (RGN-259, 0.1%) in patients with severe dry eye. The treatment group showed 35.1% reduction in ocular discomfort and 59.1% reduction in corneal staining versus placebo at day 56. The compound was safe and well tolerated (PMID: 25826322).
What Is Missing
There are no published Phase 2 or Phase 3 trials testing subcutaneous TB-500 for musculoskeletal repair, tendon healing, or sports injury recovery in humans. The safety data comes from IV administration in healthy volunteers, not from the subcutaneous protocols used in research settings. The tissue repair data comes primarily from animal models.
This is not a minor gap. It means the risk-benefit profile for subcutaneous TB-500 at common research doses has not been formally characterized in controlled human trials.
TB-500 Side Effects
Reported in Phase 1 Human Trials
The Phase 1 safety trials reported only mild to moderate adverse events at doses far exceeding typical research protocols. No dose-limiting toxicities were observed up to 1,260mg IV daily for 14 days.
Specific side effects documented in these trials were described as infrequent and not significantly different from placebo. The studies did not report injection site reactions because they used IV administration, not subcutaneous.
Commonly Reported in Research Settings (Anecdotal)
These are not from controlled trials. They come from practitioner reports and user communities:
- Headache. The most commonly reported side effect. Usually mild and temporary.
- Nausea. Occasionally reported, typically in the first few doses.
- Lightheadedness. Reported by some users shortly after injection.
- Injection site irritation. Redness, minor swelling, or itching at the injection site. Standard for subcutaneous injections of any kind.
- Fatigue or lethargy. Some users report temporary tiredness after injection.
Theoretical Concerns
Cancer risk. Thymosin beta-4 promotes cell migration, angiogenesis, and cell survival. These same mechanisms that support tissue repair could theoretically support tumor growth. Some preclinical research has explored whether thymosin beta-4 plays a role in tumor progression. The existing human safety data did not show cancer signals, but trial durations were short and not designed to detect long-term oncologic outcomes.
Anyone with active malignancy or a history of cancer should discuss this concern with an oncologist before considering any peptide that promotes angiogenesis or cell proliferation.
Immune effects. Thymosin beta-4 interacts with immune cell function. The long-term effects of exogenous supplementation on immune regulation have not been characterized in humans.
Who Should NOT Use TB-500
TB-500 is not FDA-approved. No prescribing label exists with formal contraindications. The following are precautionary based on the peptide's known mechanisms and general medical principles:
- Active malignancy or history of cancer. TB-500 promotes angiogenesis and cell migration. These are mechanisms cancer exploits to grow and spread.
- Pregnancy or breastfeeding. No safety data exists for these populations.
- Competitive athletes. TB-500 (thymosin beta-4) is on the WADA Prohibited List under S2 (Peptide Hormones, Growth Factors, Related Substances). It is banned both in-competition and out-of-competition. Detection methods exist and are used in anti-doping testing.
- Individuals on anticoagulants or with bleeding disorders. Thymosin beta-4 interacts with platelet function and wound healing pathways. Exercise additional caution.
- Anyone under 18. No pediatric safety data exists.
Frequently Asked Questions
What is the standard TB-500 dosage?
The most commonly reported research protocol uses a loading phase of 2-2.5mg subcutaneous injection twice per week for 4-6 weeks, followed by a maintenance phase of 2mg once per week. Total weekly loading dose ranges from 4-5mg. These numbers come from research literature and practitioner reports, not from FDA-approved prescribing information.
How long does TB-500 take to work?
Most research protocols report that initial effects begin during the loading phase (weeks 2-4). The full cycle of 8-12 weeks is typically completed before assessing outcomes. No controlled human trial has established a specific onset timeline for TB-500 in musculoskeletal applications.
Can TB-500 be taken orally?
TB-500 is a peptide, and peptides are generally broken down by digestive enzymes before they can be absorbed intact. The standard research route is subcutaneous injection. Oral peptide delivery is an active area of research, but standard TB-500 protocols use injection.
Should I inject TB-500 near the injury site?
Some protocols call for injecting near the area of injury, while others use standard abdominal subcutaneous injection. Thymosin beta-4 is a small, systemically distributed peptide. No published research confirms that injection site proximity to injury changes outcomes. Systemic distribution after subcutaneous injection means the peptide reaches tissues throughout the body regardless of where it is injected.
Is TB-500 the same as thymosin beta-4?
Not exactly. Thymosin beta-4 is the full-length, naturally occurring 43-amino acid peptide. TB-500 is a synthetic version designed to replicate the active region of thymosin beta-4. Published research studies thymosin beta-4 specifically. Results are applied to TB-500 based on structural similarity, but they are distinct molecules.
Can I stack TB-500 with BPC-157?
Some research protocols combine TB-500 and BPC-157, often called the "Wolverine Stack." The theory is that their different mechanisms (TB-500 for cell migration and angiogenesis, BPC-157 for growth factor signaling) produce complementary effects. No published clinical trial has tested this combination in humans. Speak with a healthcare provider before combining research peptides.
Is TB-500 banned in sports?
Yes. TB-500 (thymosin beta-4) appears on the World Anti-Doping Agency (WADA) Prohibited List under category S2: Peptide Hormones, Growth Factors, Related Substances and Mimetics. It is banned both in-competition and out-of-competition. Athletes subject to anti-doping testing who use TB-500 risk sanctions including suspension.
How should TB-500 be stored?
Store unreconstituted (powder) vials at room temperature or refrigerated. Once reconstituted with bacteriostatic water, store refrigerated at 2-8 degrees Celsius and use within 3-4 weeks. Never freeze reconstituted peptide solution.
Final Thoughts
TB-500 is one of the most researched tissue repair peptides in preclinical science. Thymosin beta-4 has documented effects on cell migration, angiogenesis, inflammation reduction, anti-fibrotic activity, and cell survival across dozens of animal studies and in vitro experiments.
The human data is limited but encouraging from a safety standpoint. Two Phase 1 trials showed thymosin beta-4 was well tolerated at doses far exceeding typical research protocols, with no serious adverse events or dose-limiting toxicities.
What is missing: controlled human trials testing subcutaneous TB-500 for musculoskeletal repair at the doses used in research protocols. The loading/maintenance dosing structure (2-5mg twice weekly, then 2mg weekly) comes from practitioner experience and animal data extrapolation, not from human efficacy trials.
If you are considering TB-500 for tissue repair, understand that you are working with a compound that has strong preclinical evidence, a favorable preliminary safety profile, and very little controlled human outcomes data. That is a more honest framing than most sources will give you.
Talk to a healthcare provider. Get baseline bloodwork. Monitor during use. Do not assume safety data from IV trials directly translates to subcutaneous protocols.
Medical Disclaimer: The information on this website is for educational and informational purposes only. It is not intended as medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before starting any peptide protocol, medication, or supplement regimen. Individual results vary. The author shares published research and available data, not medical recommendations.
Sources
- A randomized, placebo-controlled, single and multiple dose study of intravenous thymosin beta4 in healthy volunteers - Ruff D, et al. Ann N Y Acad Sci, 2010 (PMID: 20536472)
- A first-in-human, randomized, double-blind, single- and multiple-dose, phase I study of recombinant human thymosin beta4 in healthy Chinese volunteers - Wang X, et al. J Cell Mol Med, 2021 (PMID: 34346165)
- Thymosin beta4: a multi-functional regenerative peptide. Basic properties and clinical applications - Goldstein AL, et al. Expert Opin Biol Ther, 2012 (PMID: 22074294)
- Development of thymosin beta4 for treatment of patients with ischemic heart disease - Crockford D. Ann N Y Acad Sci, 2007 (PMID: 17947592)
- Animal studies with thymosin beta, a multifunctional tissue repair and regeneration peptide - Philp D, Kleinman HK. Ann N Y Acad Sci, 2010 (PMID: 20536453)
- Thymosin beta 4 promotes corneal wound healing and decreases inflammation in vivo following alkali injury - Sosne G, et al. Exp Eye Res, 2002 (PMID: 11950239)
- Thymosin beta4 and the anti-fibrotic switch - Kleinman HK, et al. Int Immunopharmacol, 2023 (PMID: 36580759)
- Thymosin beta4 limits inflammation through autophagy - Renga G, et al. Expert Opin Biol Ther, 2018 (PMID: 30063848)
- Thymosin beta4 significantly improves signs and symptoms of severe dry eye in a phase 2 randomized trial - Sosne G, et al. Cornea, 2015 (PMID: 25826322)
- Thymosin beta4 Promotes Dermal Healing - Kleinman HK, Sosne G. Vitam Horm, 2016 (PMID: 27450738)
- Evaluation of skeletal and cardiac muscle function after chronic administration of thymosin beta-4 in the dystrophin deficient mouse - Spurney CF, et al. PLoS One, 2010 (PMID: 20126456)
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